static double doubleProduct(Iterable<Double> l) {
  double prod = 1;
  fOr (Double i : l)
    if (i != null) prod *= i;
  ret prod;
}

static double doubleProduct(double... l) {
  double prod = 1;
  if (l != null) for (double i : l)
    prod *= i;
  ret prod;
}